Fiber fraction functions

class qmostetc.fiber_fraction.FiberFraction(fname=PosixPath('/builds/OpSys/etc/qmostetc/data/sersic_source_flux_loss_lut.fits'))

Calculate the sersic and point source fiber fraction from a grid

The grid needs to be stored in a FITS table with the following columns:

  • seeing: Seeing diameter [arcsec]. Typical range is 0…2.5.

  • n: Sersic index. Typical range is 0.1…10

  • r_eff: Sersic effective radius [arcsec]. Typical range is 0.1…70.

  • frac_flux_fiber: Resulting fiber flux fraction

The grid must be regular, i.e. every combination of seeing, n, and r_eff must appear exactly once.

The grid shall cover the geometry, i.e. both instrumental effects (dome seeing, telescope optics; usually a Gaussian is assumed) and the atmospheric seeing (Moffat profile).

The wavelength dependent fiber injection fraction is not included here.

Parameters:
fnamestr or pathlib.Path

File name of the lookup table.

sersic(r_eff, index, seeing)

Return the fiber fraction for a sersic profile

Parameters:
r_effastropy.units.Quantity

Sersic effective radius [arcsec]

indexfloat

Sersic index.

seeingastropy.units.Quantity

Seeing [arcsec]. This may be either a single value, or an array.

Returns:
float or numpy.ndarray

Fiber flux fraction, corresponding to the seeing parameter

point(seeing)

Return the fiber fraction for a point like source

Parameters:
seeingastropy.units.Quantity

Seeing [arcsec]. This may be either a single value, or an array.

Returns:
float or numpy.ndarray

Fiber flux fraction, corresponding to the seeing parameter